X-Ray-Contrast Gel Agents Will Help to Detect Pathologies of Different Organs More Accurately

12:46, November 2, 2021

New substances are safe for patients and cause almost no side effects

Employees of the Institute of Solid State Chemistry of the Urals Branch of the Russian Academy of Sciences and UrFU have developed new gel radiopaque contrast agents (RCAs). They are based on inorganic compounds, insoluble in water (tantalates), safe for patients, and cause no side effects. A description of the agents and the results of in vivo and in vitro experiments are presented in chapter seven of Challenges and Advances in Chemical Science.

"Tantalates based on micro- and nano-sized particles are nontoxic to the animal body and do not cause the side effects typical of iodine-containing substances. They have a pronounced ability to absorb X-rays and provide adequate X-ray images during contrast studies of hollow organs. The agents are quickly eliminated from the gastrointestinal tract without causing discomfort. Unlike iodine-containing urographine, they have neither local irritating effect on gallbladder mucosa, nor spastic action on smooth muscles of biliary tracts," explains Mikhail Zuev, professor at the Department of Physical and Colloidal Chemistry at UrFU, chief researcher at the Laboratory of Oxide Systems of the Institute of Solid State Chemistry of the UrFU RAS.

Together with employees of the Ural State Medical University, scientists conducted preclinical studies of new RCAs. They investigated the gel radiopaque agents in contrasting various hollow organs of laboratory animals. The agents showed high resolution when diagnosing the liver tree and gallbladder, as well as when diagnosing intracavitary masses in the ducts and gallbladder, when examining the stomach, duodenum, and bladder. As a result it has been established that new X-ray contrast agents are safe.

X-ray contrast agents currently used in medicine are not completely safe. Like all medical drugs, they cause a variety of effects, the scientists say.

"Many patients (probably most) who need a biliary tract x-ray have side effects such as mechanical jaundice, absorption of bile components into the bloodstream. Water-soluble iodine-containing X-ray contrast agents have local irritating and cytotoxic effect on biliary tract mucous membranes. Damage of mucous membranes leads to even greater "toxic load" on the kidneys. Thus, patients undergoing endoscopic treatment of biliary tracts are another risk group for contrast-induced nephropathy", explains Mikhail Zuev.

Contrast-induced nephropathy (CIN) is a deterioration of kidney function after intravenous injection of an x-ray contrast agent, usually temporary. But with a background of chronic kidney disease and diabetes mellitus, the risk of CIN increases by 33%. Repeated radiopaque examination with iodine preparations leads to acute renal failure in 41% of patients. To reduce complications, safer radiopaque compositions should be used. Safer in terms of toxicity may be an insoluble drug that cannot enter the bloodstream and, as a result, will not affect the development of general toxic complications, the scientists explain.

Compounds of rare earth elements (yttrium, lanthanum, gadolinium) and tantalate are the most effective in terms of radiopaque properties. In addition, the effectiveness of gel agents can be altered by using solid substitution solutions or by gradually changing the composition and average particle size of the substance.

Scientists have also developed a contrast agent based on orthotanthalate REE nanoparticles with time-long contrast enhancement. The next stage of research is clinical trials.

Reference

Recently, attention to renal complications resulting from the use of radiopaque contrast agents has increased significantly. This is attributed to the initial kidney damage. Risk factors include kidney disease, genetic predisposition, diabetes mellitus, hepatocellular insufficiency, nephrotoxic drugs, etc. In the United States, about 20 million people suffer from chronic kidney disease. This pathology occurs in 30% of the entire population over 60 years of age. Another risk group is patients with diabetes mellitus. There are more than 220 million of them in the world. According to scientists' forecasts, their number will increase by 75% in 20 years.